Well heres the top ten if its any help

1) Amphicolias

2) Argentinasaurus

3) Supersaurus

4) Futalongkasaurus

5) Sauraposeidon

6) Diplodocus

7) Antarctosaurus

8) Paralitatin

9) Turiasaurus

10) Puertasaurus

The largest dinosaur was definitely a sauropod, or long necked, quadrupedal, herbivore. However, mass estimates can be tricky with dinosaurs. The largest were either Amphicoelias (known from poorly preserved remains, so the estimate of 100 to 150 tons may not be accurate), Antarctosaurus (known from incomplete remains, but may have weighed 69 to 80 tons), or Argentinosaurus (50 to 73 tons).

I'm not sure of what fossils were found in Antarctica from all time periods, but I do know that there were a variety of plants and animals there during the Mesozoic. Some of the animals that I will list were found in Australia, which, at this time, was connected to Antarctica and had the same kinds of fauna and flora, as well as climate. Fossils of dinosaurs like Antarctopelta (an ankylosaur), Antarctosaurus (a sauropod), Cryolophosaurus (a theropod), and Leallynasaura (a small, herbivorous, bipedal dinosaur). There were amphibians, including the 16 foot long Koolasuchus, that filled a niche similar to modern crocodillians. In the shallow seas and/or rivers there were also plesiosaurs.

The plants were adapted for a cool climate with cold winters, and included conifers and ferns, as well as mosses and lichens.

Argentinosaurus is 100 tons making it the heaviest dinosaur.

Edit: Every dinosaur weight or mass you have ever heard is an estimate. Estimates are difficult when you only have the bones because of the uncertainties of unknown soft tissue. Also the largest known dinosaurs arrn't very complete which makes estimating even harder. In short there is no straight answer.

Take Brachiosaurus brancai (some call it Giraffatitan brancai ). It has been estimated as low as 15 tons and as high as 80 tons using different estimates.
Those two estimates are extreme and are generally thought to be wrong. Most estimates these days put it in the 25-30 ton range.

Argentinosaurus is undoubtingly a massive animal but it isn't fully known. There are a lot of uncertainties as to its exact proportions. Estimates have ranged from 60 -100 tons.

There are other, even less complete giant dinosaurs which 'might' be bigger.

Here are some other potential candidates to look into:
Amphicoelias, Futalognkosaurus, Puertasaurus, Paralititan, Antarctosaurus, Sauroposeidon, Turiasaurus